Franco isn’t a natural fit as Oz, but the actor’s tendency toward unsavory ambivalence actually works to his advantage as the greedy, yellow-bellied con artist. Exposed as a fraud almost immediately, he’s propped up as the savior of Emerald City while the women with real stakes in the game jostle for power and revenge. We’re never supposed to fully embrace him, and Franco’s toothy huckster grin ensures that we never quite do. But we at least understand him. More important, we understand why a band of Emerald City insiders play along with his charade.

While it does put the pieces in place for Dorothy’s eventual arrival, “Oz” is more focused on how this diverse community unites to defend its wholesome way of life against blackhearted evil. As is often the case, it’s the determined and nurturing woman behind the man, in this case Glinda, played to understated perfection by Williams, who helps them all — even Oz — believe in and save themselves. It’s a little bit corny and sometimes too in love with its own cleverness — but it’s also the most fun I’ve had at the movies this year.

Alison Gang is the U-T’s movie critic. Email her at alison@alisongang.com